Systems and methods for predicting and preventing a cabinet strike event in a washing machine appliance

ABSTRACT

Systems and methods for predicting and preventing a cabinet strike event in a washing machine appliance are provided. An exemplary method includes ramping a target speed of a motor from a first speed to a second speed over a ramping period. The method includes computing an average deviation of an observed speed of the motor from the target speed over the ramping period. The method includes computing an average power consumption by the motor over the ramping period. The method includes determining whether both the average deviation is greater than a first threshold value and the average power consumption is greater than a second threshold value. The method includes rebalancing the load if both the average deviation is greater than a first threshold value and the average power consumption is greater than a second threshold value. The method includes performing one or more standard operations if both conditions are not satisfied.

PRIORITY CLAIM

The present application is a divisional of U.S. application Ser. No.15/374,231, filed on Dec. 9, 2016, now U.S. Pat. No. 10,047,471 titled“Systems and Methods for Predicting and Preventing a Cabinet StrikeEvent in a Washing Machine Appliance,” which claims the benefit of U.S.application Ser. No. 14/079,064, filed on Nov. 13, 2013, now U.S. Pat.No. 9,518,351 titled “Systems and Methods for Predicting and Preventinga Cabinet Strike Event in a Washing Machine Appliance.” Applicant claimspriority to and benefit of all such applications and incorporate allsuch applications herein by reference.

FIELD OF THE INVENTION

The present disclosure relates generally to washing machine appliances.In particular, the present disclosure relates to systems and methods forpredicting and preventing a cabinet strike event in a washing machineappliance.

BACKGROUND OF THE INVENTION

Washing machine appliances generally include a drum rotatably mountedwithin a tub of a cabinet. The drum defines a wash chamber for receivingarticles for washing. During operation of washing machine appliances,wash fluid is directed into the tub and onto articles within the washchamber of the drum. The motor can rotate the drum at various speeds toagitate articles within the wash chamber in wash fluid, to wring washfluid from articles within the wash chamber, etc.

In particular, after the articles of clothing have been washed, thewashing machine can drain the wash fluid and then spin the drum at ahigh speed in order to relieve the articles of clothing of remainingmoisture and fluid. This process is generally known as a spin cycle or aspin out process.

In certain circumstances, prior to a spin cycle, the load in the washingmachine can become imbalanced. In particular, the articles of clothingcan become disproportionately distributed to a single location and forman out of balance mass. For example, the articles of clothing can adheretogether at a single location.

Such out of balance mass can cause a number of problems if it remainsuncorrected and present during the spin cycle. In particular, theimbalanced mass can alter the center of mass for the drum and load as awhole so that the center of mass is no longer aligned with a shaftcenter of the washing machine. Rotating the drum at high speeds, forexample during a spin cycle, in such condition can cause undesirablevibration, noise, or other damage to system components, including damagecaused by the drum becoming so far misaligned that is strikes thewashing machine cabinet.

One potential solution to the problem of out of balance loads can be tomeasure load size, load imbalance, or other operational parameters priorto performing the spin out process. If such measurements indicate aparticularly large load imbalance, then the spin out process can bedelayed while the load is rebalanced.

As an example, a washing machine according to the present disclosure canbe configured to measure the load size or other operational parameterswhile the washing machine motor is operated so as to dwell at arelatively low speed, such as, for example, 100 revolutions per minute.However, similar to the spin out process, this measurement process alsosuffers from the potential occurrence of cabinet strike events.

Therefore, systems and methods for predicting and preventing a cabinetstrike event in a washing machine appliance are desirable. Inparticular, systems and methods for predicting whether cabinet strikeevents will occur at relatively low dwelling speeds associated with ameasurement process are desirable.

BRIEF DESCRIPTION OF THE INVENTION

Additional aspects and advantages of the invention will be set forth inpart in the following description, or may be apparent from thedescription, or may be learned through practice of the invention.

One aspect of the present disclosure is directed to a washing machineappliance. The washing machine appliance includes a cabinet, a tubpositioned within the cabinet, and a drum rotatably mounted within thetub. The drum defines a wash chamber for receipt of articles forwashing. The washing machine appliance includes a motor in mechanicalcommunication with the drum. The motor is configured for selectivelyrotating the drum within the tub. The washing machine appliance includesa controller in operative communication with the motor and configured toperform operations. The operations include operating the motor to rotatethe drum for a first time period. A target motor speed is ramped from afirst speed to a second speed during the first time period. Theoperations include determining an average deviation of an actual speedof the motor from the target motor speed over the first time period andcomparing the average deviation to a first threshold value. Theoperations include determining an average power consumption of the motorover the first time period and comparing the average power consumptionto a second threshold value. The operations include performing arebalancing process when both the average deviation is greater than thefirst threshold value and the average power consumption is greater thanthe second threshold value.

Another aspect of the present disclosure is directed to a method forpredicting and preventing a cabinet strike event in a washing machine.The washing machine includes a motor configured to rotate a basket. Themethod includes operating the motor to rotate the basket for a firsttime period. A target motor speed is ramped from a first speed to asecond speed during the first time period. The method includesdetermining an average deviation of an actual speed of the motor fromthe target motor speed over the first time period and comparing theaverage deviation to a first threshold value. The method includesdetermining an average power consumption of the motor over the firsttime period and comparing the average power consumption to a secondthreshold value. The method includes performing a rebalancing processwhen both the average deviation is greater than the first thresholdvalue and the average power consumption is greater than the secondthreshold value. The method includes performing a measurement processwhen either the average deviation is less than the first threshold valueor the average power consumption is less than the second thresholdvalue. The measurement process includes operating the motor to rotatethe basket at a third speed that is greater than the second speed.

Another aspect of the present disclosure is directed to a method fordetermining whether to rebalance a load in a washing machine. Thewashing machine includes a motor. The method includes ramping a targetspeed of the motor from 60 revolutions per minute to 90 revolutions perminute over a ramping period. The method includes computing an averagedeviation of an observed speed of the motor from the target speed overthe ramping period. The method includes computing an average powerconsumption by the motor over the ramping period. The method includesdetermining whether both the average deviation is greater than a firstthreshold value and the average power consumption is greater than asecond threshold value. The method includes rebalancing the load when itis determined that both the average deviation is greater than the firstthreshold value and the average power consumption is greater than thesecond threshold value. The method includes performing one or morestandard operations when it is not determined that both the averagedeviation is greater than the first threshold value and the averagepower consumption is greater than the second threshold value.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 depicts a front, elevation view of a washing machine applianceaccording to an exemplary embodiment of the present disclosure;

FIG. 2 depicts a side, section view of the exemplary washing machineappliance of FIG. 1;

FIG. 3 provides a flow chart of an exemplary method for operating awashing machine appliance according to an exemplary embodiment of thepresent disclosure;

FIG. 4 provides a graphical depiction of actual motor speed versus timefor an exemplary washing machine appliance;

FIG. 5 provides a graphical depiction of actual motor speed versus timefor an exemplary washing machine appliance;

FIG. 6 provides a graphical depiction of motor power consumption versustime for an exemplary washing machine appliance;

FIG. 7 provides a graphical depiction of motor power consumption versustime for an exemplary washing machine appliance;

FIG. 8 provides a graphical depiction of various operational parametersversus time for an exemplary washing machine appliance according to anexemplary embodiment of the present disclosure; and

FIG. 9 provides a graphical depiction of average power consumptions andaverage speed deviations for an exemplary washing machine applianceaccording to an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

FIG. 1 provides a front, elevation view of an exemplary horizontal axiswashing machine appliance 100. FIG. 2 provides a side, section view ofwashing machine appliance 100. As may be seen in FIG. 1, washing machineappliance 100 includes a cabinet 102 that extends between a top portion103 and a bottom portion 105, e.g., along a vertical direction. Cabinet102 also includes a front panel 104. A door 112 is mounted to frontpanel 104 and is rotatable about a hinge (not shown) between an openposition facilitating access to a wash drum or basket 120 (FIG. 2)located within cabinet 102, and a closed position (shown in FIG. 1)hindering access to basket 120. A user may pull on a handle 113 in orderto adjust door 112 between the open position and the closed position.

A control panel 108 including a plurality of input selectors 110 iscoupled to front panel 104. Control panel 108 and input selectors 110collectively form a user interface input for operator selection ofmachine cycles and features. For example, in one embodiment, a display111 indicates selected features, a countdown timer, and/or other itemsof interest to machine users.

Referring now to FIG. 2, a tub 114 defines a wash fluid compartment 119configured for receipt of a washing fluid. Thus, tub 114 is configuredfor containing washing fluid, e.g., during operation of washing machineappliance 100. Washing fluid disposed within tub 114 may include atleast one of water, fabric softener, bleach, and detergent. Tub 114includes a back wall 116 and a sidewall 118 and also extends between atop 115 and a bottom 117, e.g., along the vertical direction.

Basket 120 is rotatably mounted within tub 114 in a spaced apartrelationship from tub sidewall 118 and the tub back wall 116. Basket 120defines a wash chamber 121 and an opening 122. Opening 122 of basket 120permits access to wash chamber 121 of basket 120, e.g., in order to loadarticles into basket 120 and remove articles from basket 120. Basket 120also defines a plurality of perforations 124 to facilitate fluidcommunication between an interior of basket 120 and tub 114. A sump 107is defined by tub 114 and is configured for receipt of washing fluidduring operation of appliance 100. For example, during operation ofappliance 100, washing fluid may be urged by gravity from basket 120 tosump 107 through plurality of perforations 124.

A spout 130 is configured for directing a flow of fluid into tub 114.Spout 130 may be in fluid communication with a water supply (not shown)in order to direct fluid (e.g., clean water) into tub 114. A pumpassembly 150 (shown schematically in FIG. 2) is located beneath tub 114for draining tub 114 of fluid. Pump assembly 150 is in fluidcommunication with sump 107 of tub 114 via a conduit 170. Thus, conduit170 directs fluid from tub 114 to pump assembly 150. Pump assembly 150is also in fluid communication with a drain 140 via piping 174. Pumpassembly 150 can urge fluid disposed in sump 107 to drain 140 duringoperation of appliance 100 in order to remove fluid from tub 114. Fluidreceived by drain 140 from pump assembly 150 is directed out ofappliance 100, e.g., to a sewer or septic system.

In addition, pump assembly 150 is configured for recirculating washingfluid within tub 114. Thus, pump assembly 150 is configured for urgingfluid from sump 107, e.g., to spout 130. For example, pump assembly 150may urge washing fluid in sump 107 to spout 130 via hose 176 duringoperation of appliance 100 in order to assist in cleaning articlesdisposed in basket 120. It should be understood that conduit 170, piping174, and hose 176 may be constructed of any suitable mechanism fordirecting fluid, e.g., a pipe, duct, conduit, hose, or tube, and are notlimited to any particular type of mechanism.

A motor 128 is in mechanical communication with basket 120 in order toselectively rotate basket 120, e.g., during an agitation or a rinsecycle of washing machine appliance 100 as described below. Ribs 126extend from basket 120 into wash chamber 121. Ribs 126 assist agitationof articles disposed within wash chamber 121 during operation of washingmachine appliance 100. For example, ribs 126 may lift articles disposedin basket 120 during rotation of basket 120.

A drawer 109 is slidably mounted within front panel 104. Drawer 109receives a fluid additive (e.g., detergent, fabric softener, bleach, orany other suitable liquid) and directs the fluid additive to wash fluidcompartment 119 during operation of washing machine appliance 100.Additionally, a reservoir 160 is disposed within cabinet 102. Reservoir160 is also configured for receipt of fluid additive for use duringoperation of washing machine appliance 100 (shown in FIG. 1). Reservoir160 is sized such that a volume of fluid additive sufficient for aplurality or multitude of wash cycles of washing machine appliance 100may fill reservoir 160. Thus, for example, a user can fill reservoir 160with fluid additive and operate washing machine appliance 100 for aplurality of wash cycles without refilling reservoir 160 with fluidadditive. A reservoir pump 162 is configured for selective delivery ofthe fluid additive from reservoir 160 to tub 114.

Also shown in FIG. 2 is a balancing apparatus 190. For example,balancing apparatus 190 can include a balancing ring. The balancing ringcan have an annular cavity in which a balancing material is free torotate and move about. For example, the balancing material can be afluid such as water or can be balancing balls. The balancing ring caninclude one or more interior baffles.

Although a single balancing ring or apparatus 190 is shown in FIG. 2,any number of such rings or apparatuses can be included in washingmachine appliance 100 and can be placed according to any known ordesirable configuration. For example, two balancing rings can berespectively placed at the front and back of basket 120.

Operation of washing machine appliance 100 is controlled by a processingdevice or controller 180 that is operatively coupled to control panel108 for user manipulation to select washing machine cycles and features.In response to user manipulation of control panel 108, controller 180operates the various components of washing machine appliance 100 toexecute selected machine cycles and features.

Controller 180 may include a memory and microprocessor, such as ageneral or special purpose microprocessor operable to executeprogramming instructions or micro-control code associated with acleaning cycle. The memory may represent random access memory such asDRAM, or read only memory such as ROM or FLASH. In one embodiment, theprocessor executes programming instructions stored in memory. The memorymay be a separate component from the processor or may be includedonboard within the processor. Alternatively, controller 180 may beconstructed without using a microprocessor, e.g., using a combination ofdiscrete analog and/or digital logic circuitry (such as switches,amplifiers, integrators, comparators, flip-flops, AND gates, and thelike) to perform control functionality instead of relying upon software.Control panel 108 and other components of washing machine appliance 100may be in communication with controller 180 via one or more signal linesor shared communication busses.

Controller 180 is in operative communication with motor 128. Thus,controller 180 can selectively activate and operate motor 128, e.g.,depending upon a wash cycle selected by a user of washing machineappliance 100. Controller 180 is also configured for monitoring a powerdelivered to motor 128. As will be understood by those skilled in theart, power delivered to motor 128 can be measured or determined bycontroller 180 utilizing various methods. As an example, controller 180or motor 128 may include a power measurement circuit. In alternativeexemplary embodiments, controller 180 may monitor the power delivered tomotor 128 utilizing any other suitable mechanism or method including,for example, by measuring an inverter current, a motor phase current, aphase-to-phase voltage or other operating parameters such as a motorefficiency and/or a motor power factor.

Likewise, controller 180 or other processing components of washingmachine appliance 100 can determine a current speed of motor 128according to any known techniques. For example, a speed signaldescribing the current speed of the motor can be created and provided tocontroller 180 according to back electromotive force techniques or basedon the output of one or more sensors or other components including, forexample, an optical sensor or magnetic-based sensors such as hall effectsensors.

In an illustrative example of operation of washing machine appliance100, laundry items are loaded into basket 120, and washing operation isinitiated through operator manipulation of input selectors 110. Tub 114is filled with water and detergent to form a wash fluid. One or morevalves (not shown) can be actuated by controller 180 to provide forfilling tub 114 to the appropriate level for the amount of articlesbeing washed. Once tub 114 is properly filled with wash fluid, thecontents of basket 120 are agitated with ribs 126 for cleansing oflaundry items in basket 120.

After the agitation phase of the wash cycle is completed, tub 114 isdrained. Laundry articles can then be rinsed by again adding wash fluidto tub 114, depending on the particulars of the cleaning cycle selectedby a user, ribs 126 may again provide agitation within wash chamber 121.One or more spin cycles may also be used. In particular, a spin cyclemay be applied after the wash cycle and/or after the rinse cycle inorder to wring wash fluid from the articles being washed. During a spincycle, basket 120 is rotated at relatively high speeds.

While described in the context of a specific embodiment of horizontalaxis washing machine appliance 100, it will be understood thathorizontal axis washing machine appliance 100 is provided by way ofexample only. Other washing machine appliances having differentconfigurations, different appearances, and/or different features mayalso be utilized with the present subject matter as well, including, forexample, vertical axis washing machine appliances. Thus, the teachingsof the present disclosure are not limited to use with washing machineappliance 100.

FIG. 3 depicts an exemplary method (300) for operating a washing machineappliance according to an exemplary embodiment of the presentdisclosure. Method (300) can be implemented using any suitableappliance, including, for example, washing machine appliance 100 of FIG.1.

In addition, FIG. 3 depicts steps performed in a particular order forpurposes of illustration and discussion. Those of ordinary skill in theart, using the disclosures provided herein, will understand that thevarious steps method (300) can be omitted, adapted, and/or rearranged invarious ways without departing from the scope of the present disclosure.

At (302) the target speed of the washing machine motor can be rampedfrom a first speed to a second speed. As an example, the target speed ofthe washing machine motor can be ramped from 60 revolutions per minute(RPM) to 90 RPM over a ramping period. In some implementations, thetarget speed of the washing machine motor can be ramped at about 10 RPMper second, such that the ramping period is about 3 to 4 seconds induration.

Generally, as will be discussed further below, ramping from the firstspeed to the second speed should provide sufficient rotation of thebasket or drum such that data can be collected for predicting a cabinetstrike event. However, a speed should not be reached at which a cabinetstrike event might actually occur. First and second speeds of 60 RPM and90 RPM satisfy these goals.

At (304) an average deviation of the actual speed of the motor from thetarget speed of the motor over the ramping period can be computed. Inparticular, a plurality of samples of the deviation of the actual motorspeed from the target motor speed can be collected while the targetspeed is ramped from the first speed to the second speed (e.g. duringthe ramping period). For example, actual motor speed can be determinedbased on feedback from one or more sensors such as optical sensors ormagnetometers or can be computed based on back electromotive force data.

Each sample of the deviation can be determined by comparing the actualmotor speed observed at the time of sampling to the target motor speedin effect at the time of sampling. For example, the deviation can be anabsolute value of the difference between actual and target motor speeds.

Thus, at (304) an average deviation exhibited by all collected samplescan be computed. As an example, a running average of the deviation canbe computed in real-time during the ramping period. As another example,the average can be computed after the ramping period has been completed.

As an example, FIG. 4 provides a graphical depiction 400 of actual motorspeed 402 versus time for an exemplary washing machine appliance. Moreparticularly, graphical depiction 400 depicts actual motor speed 402 asa target motor speed 404 is ramped from about 60 RPM to about 90 RPM. Ascan be seen, the actual motor speed 402 fluctuates about the targetmotor speed 404 in a periodic fashion due to the natural operatingparameters and environmental factors of the washing machine appliance.

The motor speed data depicted in FIG. 4 was collected from an exemplarywashing machine appliance containing a total load of about 12 poundswith 0 pounds of such load being out of balance. Thus, the load wasevenly distributed.

Likewise, FIG. 5 provides a graphical depiction 500 of actual motorspeed 502 versus time for an exemplary washing machine appliance. Moreparticularly, graphical depiction 500 depicts actual motor speed 502 asa target motor speed 504 is ramped from about 60 RPM to about 90 RPM.

The motor speed data depicted in FIG. 5 was collected from an exemplarywashing machine appliance containing a total load of about 7.5 poundswith all 7.5 pounds of such load being out of balance. Therefore, theload associated with the data depicted in FIG. 5 is significantly moreout of balance than the load associated with the data depicted in FIG.4.

As can be seen by comparing FIG. 4 and FIG. 5 to each other, the actualmotor speed 502 of FIG. 5 demonstrates a significantly larger deviationfrom target speed 504 than actual motor speed 402 of FIG. 4 demonstrateswith respect to target speed 404. In particular, the larger out ofbalance mass included in the washing machine appliance associated withFIG. 5 significantly increases such deviation while the balanced massassociated with FIG. 4 does not result in a significant deviation.

Returning to FIG. 3, at (306) an average power consumption of thewashing machine motor over the ramping period can be computed. Inparticular, a plurality of samples of motor power consumption can becollected while the target speed is ramped from the first speed to thesecond speed (e.g. during the ramping period). Motor power consumptioncan be computed based on various operating characteristics including,for example, an inverter current, a motor phase current, aphase-to-phase voltage, or by using various sensors including, forexample, a wattmeter and/or an ammeter.

Thus, at (306) an average power consumption exhibited by all samplescollected during the ramping period can be computed. As an example, arunning average of the power consumption can be computed in real-timeduring the ramping period. As another example, the average can becomputed after the ramping period has been completed.

As an example, FIG. 6 provides a graphical depiction 600 of motor powerconsumption 602 versus time for an exemplary washing machine appliance.More particularly, graphical depiction 600 depicts motor powerconsumption 602 as the target motor speed is ramped from about 60 RPM toabout 90 RPM. As can be seen, the motor power consumption 602 fluctuatesin a periodic fashion due to the natural operating parameters andenvironmental factors of the washing machine appliance.

The power consumption data depicted in FIG. 6 was collected from anexemplary washing machine appliance containing a total load of about 12pounds with 0 pounds of such load being out of balance.

Likewise, FIG. 7 provides a graphical depiction 700 of motor powerconsumption 702 versus time for an exemplary washing machine appliance.More particularly, graphical depiction 700 depicts motor powerconsumption 702 as the target motor speed is ramped from about 60 RPM toabout 90 RPM.

The power consumption data depicted in FIG. 7 was collected from anexemplary washing machine appliance containing a total load of about 7.5pounds with all 7.5 pounds of such load being out of balance. Therefore,the load associated with the data depicted in FIG. 7 is significantlymore out of balance than the load associated with the data depicted inFIG. 6.

As can be seen by comparing FIG. 6 and FIG. 7 to each other, the motorpower consumption 702 of FIG. 7 demonstrates significantly larger localmaximums (e.g. ranging from about 60 to 80 Watts) than the localmaximums demonstrated by motor power consumption 602 of FIG. 6 (e.g.ranging from about 30 to 40 Watts). In particular, the larger out ofbalance mass included in the washing machine appliance associated withFIG. 7 significantly increases the power consumed by the motor to rotatethe basket during certain portions of the rotational period. On theother hand, the balanced load associated with FIG. 6 does not result insuch a significant increase in power consumption.

FIG. 8 provides a graphical depiction 800 of various operationalparameters versus time for an exemplary washing machine applianceaccording to an exemplary embodiment of the present disclosure. Inparticular, graphical depiction 800 shows actual motor speed 802 inconjunction with a plot 804 of a running average of speed deviation anda plot 806 of a running average of power consumption.

As shown on the left-hand vertical axis of graphical depiction 800, theplot 804 of the running average of speed deviation is shown in units ofrevolutions per minute times 32. This numerical format can be used toretain decimal-level accuracy when certain operations of the presentdisclosure are performed using binary representations of the operatingparameters. However, such formatting is provided by way of example onlyand the systems and methods of the present disclosure can be performedaccording to any suitable numerical formatting or representation.

Likewise, as shown on the right-hand vertical axis of graphicaldepiction 800, the plot 806 of the running average of power consumptionis shown in units of Watts times 32 for similar reasons as thosediscussed above with respect to plot 804. The actual motor speed 802 isnot to scale in terms of units with respect to either plot 804 or plot806 and is therefore provided for the purposes of explanation only.

As depicted in FIG. 8, computation of the running average of speeddeviation can begin at time 810 when the actual motor speed 802 reachesa first speed of the ramping period. As an example, the first speed atwhich the computation of the running averages begin can be 60 RPM.

Samples of the deviation of the actual motor speed 802 from the targetmotor speed can be collected while actual motor speed 802 is ramped to asecond speed. For example, the second speed can be 90 RPM. A runningaverage of the collected samples can be calculated in real-time, asshown by plot 804. In particular, the running average of speed deviationcan be a cumulative running average of all collected samples.

Likewise, the running average of motor power consumption can also beginbeing computed at time 810. Samples of the motor power consumption canbe collected while actual speed 802 is ramped to a second speed. Arunning average of the collected samples of motor power consumption canbe calculated in real-time, as shown by plot 806. In particular, therunning average of power consumption can be a cumulative running averageof all collected samples.

Once the actual motor speed 802 reaches the second speed at time 820,computation of the running average of speed deviation and the runningaverage of power consumption can cease. Thus, the most recently computedvalues for the running average of speed deviation and the runningaverage of power consumption at time 820 can be used as the finalaverages over the ramping period.

It should be appreciated, however, that the data provided in FIGS. 4, 5,6, 7, 8, and 9 are representative of an exemplary embodiment of awashing machine. The present disclosure is in no way limited to theparticular values shown by such data. As different washing machineappliances have varying components, designs, attributes, operationalparameters, or other design variables or objectives, application of theteachings and disclosures of the present disclosure to different washingappliances can result in varying operational data and threshold limits.

Returning to FIG. 3, at (308) it can be determined whether both theaverage deviation is greater than a first threshold value and theaverage power consumption is greater than a second threshold value. Forexample, the first and second threshold values can be retrieved frommemory such as a lookup table or can be computed according to a transferfunction.

If it is determined that both the average deviation is greater than thefirst threshold value and the average power consumption is greater thanthe second threshold value then method (300) can proceed to (310) andrebalance the load. In particular, if both the average power consumptionand the average speed deviation are greater than their respectivethreshold values, then it can be assumed that the load contains anunacceptably large imbalance. Therefore, the rebalancing process shouldbe performed prior to continuing standard operations, such as ameasurement process or a high speed spin cycle. In such fashion, acabinet strike event that would likely occur during such standardoperations can be avoided.

Rebalancing the load at (310) can include any operational process ortechnique that provides for a rebalancing of the load. For example, thebasket can rotate slowly to allow the out of balance mass to tumble downand be disrupted. Generally, any known technique to rebalance the loadcan be performed at (310).

However, if it is determined that either the average deviation is notgreater than the first threshold value or the average power consumptionis not greater than the second threshold value, the method (300) canproceed to (312) and continue with standard operations. In particular,if one or both of the average deviation or average power consumption areless than their respective threshold values, then it can be assumed thatthe load does not contain an unacceptably large imbalance. Therefore, asan example, a measurement process which dwells at a relatively low speedcan be performed at (312) without experiencing a cabinet strike event.For example, the measurement process can include operating the motor torotate at about 100 RPM. As another example, the standard operationsperformed at (312) can include any known process or technique forreducing the fluid content of the articles of clothing in the basket,including spinning the basket at a high speed.

As an example, FIG. 9 provides a graphical depiction 900 of averagepower consumptions and average speed deviations for an exemplary washingmachine appliance according to an exemplary embodiment of the presentdisclosure. In particular, graphical depiction 900 shows a plurality ofmeasurements of average power consumption and average speed deviationfor a plurality of different load sizes and load imbalances as thewashing machine motor is ramped from about 60 RPM to about 90 RPM. Shownon the vertical axis is average power consumption and shown on thehorizontal axis is average speed deviation.

The plotted measurements correspond to the load values shown on theright-hand side of graphical depiction 900 which are presented in theformat of (total load, out of balance load). For example, dataset 902includes five different measurements of average power consumption andaverage speed deviation for a washing machine ramping a total load of 43pounds with zero of the load being out of balance. As another example,dataset 904 includes five different measurements of average powerconsumption and average speed deviation for a washing machine ramping atotal load of 31.5 pounds with 8.5 pounds of such total load being outof balance.

Also shown in graphical depiction 900 are first threshold value 906 andsecond threshold value 908. In particular, first threshold value 906 canbe a threshold speed deviation value, such as, for example, about 2.4 or3 RPM. Likewise, second threshold value 908 can be a threshold powerconsumption value, such as, for example, 37.5 Watts. However, otherthreshold values can be used for various washing machine appliances.

As discussed with respect to (308)-(312) of FIG. 3, if both the averagespeed deviation is greater than the first threshold value 906 and theaverage power consumption is greater than the second threshold value908, then it can be predicted that a cabinet strike event is likely tooccur and, therefore, the load can be rebalanced. However, if either theaverage speed deviation is less than first threshold value 906 oraverage power consumption is less than second threshold value 908, thenit can be predicted that a cabinet strike event is not likely to occurand, therefore, the washing machine appliance can proceed to performstandard or previously scheduled operations. With reference to graphicaldepiction 900, this means that measurements within the upper-rightregion of graphical depiction 900 will result in a rebalancing processwhile measurements that do not fall within such region will result inthe continued performance of standard operations, such as, for example,a low speed measurement process and/or a high speed spin out process.

One of skill in the art, in light of the disclosures provided herein,will appreciate that the data provided by the plurality of measurementsof average power consumption and average power deviation depicted ingraphical depiction 900 can be test measurements that are used todesign, select, or otherwise obtain the threshold values 906 and 908. Inparticular, such threshold values have been designed so as to assist inclassifying later observed average power consumption and average speeddeviation data as generally indicative of a load that will cause acabinet strike event or a load that will not cause a cabinet strikeevent. Thus, for example, whether a cabinet strike event occurred duringa low speed measurement process performed following each of theplurality of measurements can be used to identify the appropriatethreshold values 906 and 908.

It will be appreciated, however, that the particular threshold values906 and 908 are exemplary in nature and are driven by the particulardesign goals, constraints, and operating parameters of a particularexemplary washing machine appliance.

Instead, according to aspects of the present disclosure, thresholdvalues can be designed, selected, or obtained to assist in classifyinglater observed average power consumption and average speed deviationdata as indicative of acceptable load characteristics or unacceptableload characteristics. Such acceptable load characteristics can generallybe based on machine capabilities, design choices with respect to noise,vibration, or any other attributes, operational parameters, or otherdesign variables or objectives. In particular, the determination ofappropriate threshold values can be driven by the goal of predicting andpreventing cabinet strike events. As such, the selection of thresholdvalues can also take into account measurement process speed, measurementprocess duration, spin cycle speed, spin cycle duration, balancingapparatus capabilities, component reliabilities, wet load dynamics, orother system component variation.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A method for determining whether to rebalance aload in a washing machine, the washing machine comprising a motor, themethod comprising: ramping a target speed of the motor from 60revolutions per minute to 90 revolutions per minute over a rampingperiod; computing an average deviation of an observed speed of the motorfrom the target speed over the ramping period; computing an averagepower consumption by the motor over the ramping period; determiningwhether both the average deviation is greater than a first thresholdvalue and the average power consumption is greater than a secondthreshold value; rebalancing the load when it is determined that boththe average deviation is greater than the first threshold value and theaverage power consumption is greater than the second threshold value;and performing one or more standard operations when it is not determinedthat both the average deviation is greater than the first thresholdvalue and the average power consumption is greater than the secondthreshold value.
 2. The method of claim 1, wherein ramping the targetspeed of the motor from 60 revolutions per minute to 90 revolutions perminute over the ramping period comprises ramping the target speed at arate of about ten revolutions per minute per second.
 3. The method ofclaim 1, wherein computing the average deviation of the observed speedof the motor from the target speed over the ramping period comprisescomputing during the ramping period a running average of the absolutevalue of a deviation of the observed speed of the motor from the targetspeed.
 4. The method of claim 1, wherein computing the average powerconsumption by the motor over the ramping period comprises computingduring the ramping period a running average of the power consumption bythe motor.